JP3382278B2 - Multicolor printing apparatus and image processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor printing apparatus and image.
It relates to a processing method.

[0002]

2. Description of the Related Art Conventionally, a black-and-white printer has realized a variety of expressions by realizing logical operations at the overlapping portions of figures. For example, a logical sum is applied to an overlapping portion to realize a special drawing effect, or a logical product is applied to easily create a complicated tile pattern.

[0003]

However, in the case of a color printer, the color data is multi-valued in many cases, and it may be essentially impossible to perform the above-mentioned processing on the overlapping portion of the figures. Many. When a color graphic developed by a host connected to a color printer is represented on a CRT, the overlapping area of the expanded graphic is normally RGB.
Since it is often the case that the processing is conscious of the overlap in CR, in a printer that normally has only YMCK four-sided memory, CR
It was essentially impossible to perform color reproduction similar to T.

[0004] The present invention has been made to solve the above problems, with respect to the overlapping portion of the foreground color image, to provide a multicolor printing apparatus and an image processing method capable colorful color reproduction To aim.

[0005]

In order to achieve the above-mentioned object, the present invention is a method of converting input print data into a drawing color and expanding the same, and drawing the expanded drawing color data in a memory. In a color printing apparatus, a determination unit that determines overlapping of drawn color images, and a plurality of overlapping drawn color images that can be additively mixed according to the determination result of the determination unit are different from the color expression system of the drawn colors. And a printing unit that performs printing based on the drawing color data drawn in the memory. And In order to achieve the above object, the present invention provides an image processing method for multicolor printing, which develops input print data and draws the developed drawing color data in a memory. An expansion step of expanding the print data into drawing color data composed of an address and a plurality of color components, a judgment step of judging the color overlap of the images to be drawn, and a judgment of the color overlap portion in the judgment step . With respect to the drawing color data, a color mixture arithmetic expression of initial parameters or saturation occurs.
In this case, the saturation in which the initial parameters are rewritten is
It is characterized by including a processing step of performing processing using a color mixture arithmetic expression that is unlikely to occur and a drawing step of drawing the processed drawing color data in the memory.

[0006]

[0007]

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings. In the embodiment, the case where the color reproduction processing is applied to a color inkjet printer device having a YMCK frame sequential memory will be described in detail as an example. <Description of Printer Engine> FIG. 6 is a schematic view of a color ink jet printer IJRA in the present embodiment, and a block 1 in the schematic configuration of FIG. 1 described later.
It is also a figure which shows the general view of the color inkjet printer engine part of 20. The control units other than the block 120 shown in FIG. 1 are not shown.

In FIG. 6, a spiral groove 500 of a lead screw 5005 which is interlocked with forward and reverse rotations of a drive motor 5013 and rotates via drive force transmission gears 5011 and 5009.
The carriage HC that engages 4 has a pin (not shown) and is reciprocated in the directions of arrows a and b. An inkjet cartridge IJC is mounted on the carriage HC. A paper pressing plate 5002 presses the paper against the platen 5000 along the moving direction of the carriage. Photocouplers 5007 and 5008 are home position detecting means for recognizing the presence of the lever 5006 of the carriage in this area and switching the rotation direction of the motor 5013.

Reference numeral 5016 is a cap member for capping the entire surface of the recording head, and 5015 is a suction means for sucking the inside of the cap, which performs suction recovery of the recording head through the opening 5023 in the cap. Reference numeral 5017 is a cleaning blade, and 5019 is a member that allows this blade to move in the front-rear direction, and these are supported by a main body support plate 5018. Needless to say, a known cleaning blade can be applied to the blade instead of this form. Reference numeral 5021 denotes a lever for starting suction for suction recovery, which moves in accordance with the movement of the cam 5020 that engages with the carriage, and the driving force from the driving motor is movement-controlled by a known clutch switching transmission means. . The capping, cleaning, and suction recovery are performed by the lead screw 5 when the carriage reaches the home position side area.
Although it is configured that desired processing can be performed at the corresponding positions by the action of 005, it may be operated at timings other than these.

<Outline of Apparatus (Block Diagram)> FIG. 1 is a schematic configuration diagram of a color ink jet printer apparatus in this embodiment. 8 which is the main point in explaining this embodiment
The function of each block is described below. (1) The block 111 temporarily holds print data (RGB values) sent from the host (not shown) to this apparatus.

(2) Block 112 is provided with the given RGB
The drawing color (YMCK value) is calculated from the value, and the current color (current drawing color) is updated. RGB value to YM
Details of the process of converting to a CK value are shown in FIG. The RGB values are temporarily stored as current color values. (3) The block 113 is a development system, and a point address (x, y) uniquely corresponding to the address of each YMCK memory
To generate. The address on the YMCK memory at this time is called "drawing point pixel" and its value is called "pixel value".

(4) The block 114 is the block 1 described above.
It is checked whether or not the drawing point pixel generated in 13 is filled with the pixel value of the previously developed figure. At this time, when the drawing is already performed, it is called "the drawing point pixel is on", and when the drawing is not performed, it is called "the drawing pixel is off". (5) The block 115 performs reverse color conversion to obtain RGB values from YMCK values. This inverse color conversion is performed in block 1 above.
The inverse conversion corresponds to the color processing in 12. If the drawing pixel has already been turned on in the pixel check of the block 114 described above, in order to obtain the lost previous current RGB color value, the inverse operation is performed and the RGB value is obtained from the YMCK value. The details of this inverse calculation will be described later with reference to the diagram shown in FIG.

(6) The block 116 calculates the additive color mixture using the given arithmetic expression. Using the RGB value and the current RGB color value obtained in the above block 115 as input values, a reproduced color when additive color mixing is performed is calculated. (7) The block 117 draws a point in the memory with reference to the current color value given by the YMCK value.

(8) A block 120 is a color ink jet printer engine, which is a block for printing after all drawing is performed in the YMCK memory. The details are shown in FIG. Here, the procedure in which the data is processed is determined by the processing result in the above-mentioned block 114, and changes depending on the following conditions.

(A) Drawing in an area where figures do not overlap → blocks 111, 112, 113, 114, 117 (B) Drawing in an area where figures overlap → blocks 111, 112, 113,
114, 115, 116, 117 For example, as shown in FIG. 3, first, at the point (x ₁ , y ₁ ), the drawing pixel is off, and there is no figure in the drawing area. Then, at the point (x ₂ , y ₂ ), the drawing pixel is on and overlaps the inside of the already drawn quadrilateral area, so the above condition (B) is determined. That is, since all the drawing pixels are in the ON state in the already drawn quadrilateral area, the points (x ₂ , y ₂ ) to be newly drawn must be processed by the blocks 115 and 116 before drawing. I have to.

<Outline of Processing> Next, the processing will be described with reference to FIG.
It will be described below according to the flowchart shown in FIG. First,
In step S211, the print data sent from the host (not shown) to the apparatus is temporarily held. Next, in step S212, the drawn color (YMCK value) is calculated from the given RGB values, and the current color (current drawing color: YMCK value) is updated. The RGB value is temporarily stored as the current RGB color value. In step S213, expansion processing is performed to generate a point address (x, y) uniquely corresponding to the address of each YMCK memory. Then, in step S214, it is checked whether the drawing point pixel generated in step S213 is "ON" or "OFF". Here, if "ON", the process proceeds to step S215, and if "OFF", the process proceeds to step S217.

In step S215, R is calculated from the YMCK value.
Reverse color conversion for obtaining a GB value is performed. Next, step S2
In step 16, the additive color mixture is calculated using the given arithmetic expression. That is, the reproduced color when additive color mixing is performed using the RGB value and the current RGB color value obtained in step S215 as input values is calculated, and the current color value is updated. Next, in step S217, YMCK
Draw a point in memory with reference to the current color value given by. Then, in step S218, the end of the graphic drawing is checked, and if not completed, the process returns to step S213, and the drawing of the dot is repeated to develop one graphic. However, if it is finished, the process proceeds to step S219 to check whether all the data in the page have been drawn,
If not completed, the process returns to step S212, and if completed, the process proceeds to step S220. This step S2
In step 20, the color inkjet engine is driven to print the image drawn in the YMCK memory on paper.

<YMCK-RGB conversion / RGB-YMC
K conversion> Next, YMCK-RGB conversion and RGB-YM
The CK conversion will be described with reference to FIG. In the above-mentioned color processing block 112, RGB values are converted to density, UCR
(Undercolor removal), masking, and γ correction are performed before conversion into YMCK values. These are known processes, and are generally calculated by the following calculation formulas (input RGB, output Y ″ M ″ C ″ K ″) [density conversion] C _S = 255 * (1-log R) M _S = 255 * (1-log G) Y _S = 255 * (1-log B) where 255 is the number of RGB gradations, and the bottom of log is 255. [UCR (under color removal)] K = Min (C, M, Y) C = C S -K M = M S -K Y = Y S -K However, Min (X, Y) is compared X, the Y Returns the minimum value of the above. [Masking] C '= a ₁₁ * C + a ₁₂ * M + a ₁₃ * Y + a ₁₄ * K M' = a ₂₁ * C + a ₂₂ * M + a ₂₃ * Y + a ₂₄ * K Y '= a ₃₁ * C + a ₃₂ * M + a ₃₃ * Y + a ₃₄ * KK ′ = a ₄₁ * C + a ₄₂ * M + a ₄₃ * Y + a ₄₄ * K However, masking parameters {a ₁₁ , a ₁₂ , ..., A ₄₄ }
Is a coefficient obtained by the method of least squares. [Gamma correction] C ″ = f _c (C ′) M ″ = f _m (M ′) Y ″ = f _y (Y ′) K ″ = f _k (K ′) where f _c (x) and f _m (X), f _y (x), f _k
(X) is a function that linearly corrects the output characteristics of cyan, magenta, yellow, and black ink, respectively.

For the log calculation and the gamma correction calculation in the density conversion, a LUT is usually used, and a method of referring to a table value by an address is adopted. Also in this embodiment, an LUT is prepared and used. The upper graph shown in FIG. 5 shows a desired input / output characteristic curve. In order to realize this,
Some sample points are prepared in a table with X as an input address and Y as an output value, and these are made into a table.

Further, in order to enable the above-mentioned inverse conversion, at least the following conditions must be satisfied. (1) It is possible to uniquely perform inverse conversion without gradation saturation by gamma correction. (2) An inverse matrix exists in a 4 * 4 matrix composed of masking coefficients. Normally, it is not difficult to determine the parameters and the like so as to satisfy these conditions, and the inkjet printer according to the present embodiment is within a sufficiently feasible range. Further, although some errors occur in the inverse conversion, it is possible to put this in a practically allowable range. Therefore, the above-mentioned RGB-
YMCK-RGB conversion, which is the inverse conversion of YMCK conversion, is possible and realized as follows (input Y ″ M ″ C ″).
K ″, output RGB) [Inverse gamma correction] C ′ = F _c (C ″) (where F _c () is the inverse function of f _c ()) M ′ = F _m (M ″) (where F _m ( ) Is the inverse function of f _m ()) Y ′ = F _y (Y ″) (where F _y () is the inverse function of f _y ()) K ′ = F _k (K ″) (where F _k () is Inverse function of f _k ()) [Inverse masking] {C, M, Y} = {IM} * {C′M′Y ′} where IM is the masking parameter {a ₁₁ ,
When a ₁₂ , ..., A ₄₄ } is a 4 × 4 matrix, the 4 × 4
It is the inverse of the matrix. [Reverse UCR (Undercolor Removal)] C _S = C + K M _S = M + K Y _S = Y + K [Reverse Density Conversion] R = 255 ** (1-C _S / 255) G = 255 ** (1-M _S / 255) B = 255 ** (1 -Y S / 255) where, X ** P is a power of P in X.

The above-mentioned inverse density conversion and inverse gamma correction are performed by the above L
It is assumed that the UT is referred to, an address that hits the corresponding value is searched for, and linear interpolation is performed from the previous and next values. The lower graph shown in FIG. 5 shows the inverse transformation of the desired input / output characteristic curve. <Regarding Additive Color Mixing Calculation> In this embodiment, two colors {R
_{When 1} , G ₁ , B ₁ }, {R ₂ , G ₂ , B ₂ } are mixed, the color to be developed is defined as follows.

R = pr (R ₁ ) + qr (R ₂ ) G = pg (G ₁ ) + qg (G ₂ ) B = pb (B ₁ ) + qb (B ₂ ) However, when the maximum gradation value is exceeded Is up to the maximum value. Here, pr (), qr (), pg (), q
g (), pb (), qb () are functions having a desired characteristic curve and are approximated by LUT. By rewriting the contents of this LUT, any color mixture can be reproduced. A linear table is prepared as an initial value, and a function that gives R = pr (R) is defined. This is a color mixture that gives a linear sum of two colors, and is equivalent to applying the following arithmetic expression.

R = R ₁ + R ₂ G = G ₁ + G ₂ B = B ₁ + B _{2 In} this arithmetic expression, the saturated value is always replaced with the maximum value as follows, so that it is saturated immediately in practical use. Often.

R ₁ = 129, R ₂ = 141 R = 129 + 141 = 270 → 255 Therefore, it is conceivable to prepare an arithmetic expression such that saturation is unlikely to occur. For this purpose, it is possible to replace the contents of the LUT with desired characteristics and process. <Regarding Rewriting of LUT> Here, a process of rewriting the LUT table for color mixing will be described.
The data table is loaded sequentially and downloaded from the host in the following format.

[LUT rewriting instruction] [corresponding table designation] [data 1]
[Data 2] ... "Data 255" [EOD] Here, the corresponding table is pr (), qr (),
Corresponding to pg (), qg (), pb (), qb (), one instruction is used to rewrite one LUT.

As described above, according to this embodiment,
In a color printer having only YMCK four-sided memory, additive color mixture of the three primary colors of RGB can be realized. Also,
Even in a multi-color printing apparatus that uses a table memory and interpolation calculation in the color processing unit, YMCK-RGB conversion can be performed by performing inverse interpolation calculation by the method of creating the table memory described above. Furthermore, in the printer engine section,
The present invention is not limited to the use of a thermal transfer color printer or a color LBP engine.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Further, it goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0029]

As described above, according to the present invention,
It is possible to reproduce various colors in the overlapping portion of the drawn color images. According to the first aspect of the present invention, since the color is converted into a color expression method capable of additive color mixture and the additive color mixture processing is performed by an arbitrary color mixture arithmetic expression, color reproduction for the overlapping portion of the drawn color image is displayed on the host. The color reproduction can be performed using the same color mixture calculation formula as the color reproduction performed according to the image. According to the invention described in claim 4, the color mixture arithmetic expression of the initial parameter or the saturation occurs in the overlapping portion of the drawn color images.
In this case, the saturation in which the initial parameters are rewritten is
It is possible to perform processing using color mixing arithmetic expressions that are difficult to occur.
However, saturation has occurred in the color mixing formula of the initial parameter.
Saturation is less likely to occur in color mixing operations even when
It becomes possible to make it .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a color inkjet printer device.

FIG. 2 is a flowchart showing an outline of processing of each block in FIG.

FIG. 3 is a diagram showing a positional relationship between a figure developed in a YMCK memory and two points to be drawn.

FIG. 4 is a color processing unit (RGB-YMCK conversion, YMCK-RGB) adopted in a color inkjet printer device.
It is a schematic block diagram of (conversion).

FIG. 5 is a graph showing a characteristic curve for approximation and inverse conversion of an input / output characteristic curve by a LUT (look-up table).

FIG. 6 is a schematic view of a color inkjet printer device.

Claims (5)

(57) [Claims] 1. A conversion of input print data into a drawing color
And the expanded drawing color data is stored in the memory.
A multicolor printing apparatus for drawing in, a determination unit configured to overlap drawing color image, according to the determination result of said determination means, heavy Do that rendering color images
, Additive color mixture different from the color expression method of the drawing color is possible
A color mixture processing unit that converts into a color representation method using a plurality of color components and performs additive color mixture processing with an arbitrary color mixture arithmetic expression, and prints based on the drawing color data drawn in the memory.
Multicolor printing apparatus characterized by having a Nau printing means. 2. The color mixing arithmetic expression is further processed by an information processing device.
The multicolor printing apparatus according to claim 1, further comprising means for downloading from the multicolor printing apparatus. 3. Conversion of input print data into drawing color
And the expanded drawing color data is stored in the memory.
An image processing method for multi-color printing , wherein the overlapping drawing color images are judged according to the judgment result of the judging means.
, Additive color mixture different from the color expression method of the drawing color is possible
An image processing method characterized by converting to a color expression system and performing additive color mixing processing using an arbitrary color mixing arithmetic expression . 4. An image processing method for multicolor printing, wherein input print data is expanded, and the expanded drawing color data is drawn in a memory, wherein the input print data includes an address and a plurality of colors. An expansion step of expanding the drawing color data composed of components, a judgment step of judging the color overlap of the images to be drawn, and an initial step for the drawing color data judged to be a color overlap part in the judgment step. Parameter color mixing formula or tiredness
The initial parameters were rewritten when the sum occurred
An image processing method comprising: a processing step of performing processing using a color mixture arithmetic expression in which saturation hardly occurs; and a drawing step of drawing the processed drawing color data in the memory. 5. A process using the mixed arithmetic expression, an image processing method according to claim 4, wherein a is performed using a table.